FREMONT, Calif. (AP), May 31 - Stunts, stagecraft, scripts - and a touch of the surreal - shaped the presidential campaign Thursday as Mitt Romney and President Barack Obama sought an edge on voters' No. 1 issue, the economy.

On one coast, Romney made a surprise trip to the former California headquarters of solar-panel manufacturer Solyndra to accuse Obama of currying favor with campaign supporters by giving a federal loan to the green energy company that later went bankrupt.

``This half-a-billion-dollar taxpayer investment represents a serious conflict of interest on the part of the president and his team,'' the Republican presidential candidate said as he stood outside the shuttered company and held it up as Exhibit A of presidential missteps on the economy.

He offered no proof of his claim during a visit that was shrouded in a highly unusual amount of secrecy because, aides said, the campaign feared Obama would interfere with his Republican rival's plans to appear there.

At roughly the same time across the country in Boston, Obama's campaign staged its own event outside Massachusetts' Statehouse to argue that Romney's record as governor from 2003 to 2007 proves he is ill-prepared to manage the nation's economy.

``Romney economics didn't work then and it won't work now,'' Obama campaign strategist David Axelrod said at a news conference, pointing to a poor record of job creation, increased fees and the addition of $2.6 billion to the state's debt on Romney's watch.

Axelrod's appearance attracted several dozen Romney supporters, including many who protested loudly by chanting ``Where are the jobs?'' and holding signs that said ``Obama isn't working.''

The competing events, complete with rival Web videos and frenzied backers, made for an oddball day on the campaign trail and showed the degree to which Obama and Romney's teams are trying to undercut each other's economic credentials during the nation's slow-moving recovery, easily the top issue for voters.

The jockeying also came one day before Friday's May employment report, which will offer the latest window into the nation's economy.

Economists were expecting the report to say that employers added 158,000 jobs, which would be better than the past two months but well below the winter's pace of 252,000 jobs per month. They also expect no change in the unemployment rate, which was 8.1 percent in April.

Obama, himself, stayed above the fray of the day, embracing an opportunity to appear presidential as his Republican rival struggled to draw attention to his campaign.

The Democratic incumbent was at the White House on Thursday. He appeared with former President George W. Bush, the man he repeatedly blames for the nation's economic turmoil, for the unveiling of Bush's official portrait during a rare, nonpolitical event in an election year.

But on this day, Obama had little to say about the campaign and kept a bipartisan tone during the unveiling.

``We may have our differences politically, but the presidency transcends those differences. We all love this country,'' Obama said as the last two Republican presidents, George W. Bush, and his father, George H.W. Bush, looked on.

Romney was far more direct.

He staged what amounted to almost a taunt to the president by traveling to the shuttered Solyndra plant here. His campaign didn't announce the event location or subject in advance and barred reporters from disclosing the venue until arrival. A senior Romney aide said the campaign was concerned the Obama administration would work with local officials to prevent Romney from holding an event there.

Yet, for all the preparation, and underscoring the challenge of being the challenger, Romney's event was pre-empted by live cable TV coverage of the Bush portrait unveiling.

Solyndra has emerged as a vulnerability for Obama because the company received $535 million in loan guarantees from Obama's Energy Department in 2009 only to go bankrupt two years later, sparking an ongoing investigation. The loan guarantee program, designed to spur alternative energy projects, was created during the Bush administration.

Republicans have been assailing Obama on Solyndra for months, partly by pointing to the connection between Obama fundraisers and the company while arguing that the president used government policies to benefit campaign supporters.

Steve Spinner, a former Energy Department official, raised at least $500,000 for Obama's campaign. Emails released earlier by congressional investigators show that Spinner was actively involved in the Solyndra loan despite pledging to step aside because his wife's law firm represented the company. One of Solyndra's investors was the foundation of George Kaiser, an Oklahoma billionaire who has supported Obama.

Kaiser has said he was not active in helping Solyndra receive the loan. White House records show that Kaiser was a frequent visitor to the White House. He has said he did not discuss Solyndra on those visits, although the company's name did come up at least once during one of those visits.

The administration says the loan was awarded on the merits and that extensive GOP efforts have failed to turn up a ``smoking gun.'' The Energy Department's inspector general so far has only criticized the Energy Department for general problems with the loan program. It has not addressed charges of political cronyism.

But Romney suggested a political payoff, saying: ``Free enterprise to the president means taking money from the taxpayers and giving it freely to his friends.''

``You can shout down speakers my friends, but it's hard to Etch A Sketch the truth away,'' Axelrod responded, referring to a comment by a top Romney aide, Eric Fehrnstrom, about Romney shifting gears for the general election campaign.

Romney used his trip to Southern California to gain another type of political capital - the endorsement of former first lady Nancy Reagan. After hosting Romney and his wife, Ann, at her Los Angeles home on Thursday, the widow of President Ronald Reagan issued a statement saying that ``Ronnie'' would have joined her in liking Romney's ``business background and his strong principles.''

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Thomas reported from Washington. Associated Press writers Matthew Daly in Washington and Bob Salsberg in Boston contributed to this report.